A recent development in the field of electro-mechanics has been the miniaturization of various mechanical devices. Typical of such devices are tiny gears, levers, and valves. These "micro-mechanical" devices are manufactured using integrated circuit techniques, often together with electrical control circuitry. Common applications include accelerometers, pressure sensors, and actuators. As another example, spatial light modulators can be configured from micro-mechanical reflective pixels.
One type of micro-mechanical spatial light modulator is a digital micro-mirror device (DMD), sometimes referred to as a deformable mirror device. The DMD has an array of hundreds or thousands of tiny tilting mirrors. Light incident on the DMD is selectively reflected or not reflected from each mirror to an image plane, to form images. To permit the mirrors to tilt, each mirror is mounted on one or more post-supported hinges. The mirrors are spaced by means of air gaps, over underlying control circuitry. The control circuitry provides electrostatic forces, which cause each mirror to selectively tilt. In many DMDs, an edge of the mirror contacts a landing electrode, which serves as a stop.
After continued use of the DMD, it is possible that the hinge will undergo mechanical relaxation as the result of repeated deformation. Another factor that may cause such relaxation is operation in extreme temperatures. When relaxation of the hinge occurs, the device may no longer operate properly.